Fire Dynamics Terminology Flashcards
To enhance understanding of Terminology associated with Fire Dynamics
Autoignition
Initiation of combustion by the heat but without a spark or flame.
Autoignition Temperature
The lowest temp. at which a combustible material ignites in air without a spark of flame.
Backdraft
Instantaneous explosion or rapid burning of superheated gases that occur when oxygen is introduced into a oxygen-depleted confined space.
Carbon-Dioxide
Colourless, odourless, dangerous gas that neither supports combustion nor burns. (Used in portable Fire Extinguishers as an extinguishing agent to extinguish Class B or C fires by smothering or displacing oxygen)
Carbon Monoxide
Colourless, odourless, dangerous gas formed by the incomplete combustion of carbon.
Chemical Flame Inhibition
Extinguishment of a fire by interruption of the chemical chain reaction.
Combustion
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame.
Combustion Zone
The area around a heat source in which there is sufficient air available to feed a fire.
Conduction
Physical Flow or transfer of heat energy from one body to another, through direct contact or an intervening medium, from the point where the point where heat is produced to another location, or from a region of high temp to a region of low temp.
Energy
the capacity to perform work.
Convection
Transfer of heat by the movement of heated fluids or gases, usually in an upward direction.
Endothermic reaction
A chemical reaction in which a substance absorbs heat.
Exothermic Reaction
Chemical Reaction between two or more materials that changes the material and produces heat
Flashover
Rapid transition from the growth stage to the fully developed stage.
Fire Point
Temp. at which the a liquid fuel produces a sufficient vapours to support combustion once the fuel ignites. Fire Point is usually a few degrees above flash point.
Flammable Explosive Range
The range between the UEL and LEL to which a substance can ignite.
Fuel-Limited
Fire with adequate oxygen in which the HRR and growth rate are determined by the characteristics of the fuel.
Flash Point
Minimum temp. at which a liquid gives off enough vapours to form an ignitable mixture with air near the surface of the liquid.
Heat
Form of energy associated with the motion of the atoms and molecules which is transferred from one body to another as a result of temp. differences between the bodies.
Heat Flux
The measure of the rate of heat transfer to or from a surface, typically expressed in (kW/m2)
Heat Release Rate (HRR)
Total amount of heat release per unit time. Measured in kW or MW
Hydrogen Cyanide
Colourless, toxic, and flammable liquid until it reaches 79°(26°C). Produced by the combustion of nitrogen-bearing substances
Lower Explosive (flammable) Limit (LEL)
Lower limits at which a flammable gas or vapour will ignite and support combustion. Below this limit gases are too lean or thin to burn
Miscible
Materials that are capable of being mixed in all proportions
Piloted Ignition
Moment when a mixture of fuels and oxygen encounter and external heat source with sufficient heat or thermal energy to start the combustion reaction.
Polar Solvants
Flammable liquids that have an attraction to water.
Power
the amount of energy delivered over a given period of time.
Pyrolysis
The Chemical decomposition of a solid material by heating. Precede combustion of a solid material.
Radiation
Transmission or transfer of heat energy from one body to another body of a lower temp.through intervening space by electromagnetic waves.
Reducing Agent
Fuel that is being oxidized or burned during combustion
Rollover
Conditions in which the unburned fire gases that have accumulated at the top of a compartment ignite and flames propagate through the hot gas layer or across the ceiling.
Smoke Explosion
Forms of fire gas ignition. The ignition of accumulated flammable products of combustion and air that are within their flammable range.
Solubility
Degree to which a solid, liquid, or gas dissolves in a solvent (usually water)
Spontaneous Ignition
Initiation of combustion of a material by an internal chemical or biological reaction that has produced sufficient heat to ignite the material
Temperature
Measure of the average kinetic energy of the particles in a sample of matter, expressed in terms of units or degrees of temp.
Upper Explosive (Flammable) Limit
Upper limit at which flammable gas or vapours will ignite. Gas or vapours are too rich to burn. (Lacks proper quantity of oxygen)
Vaporization
Physcial process that changes a liquid into a gaseous state.
Ventilation-Limited
Fire with limited ventilation in which the HRR or growth is limited by the amount of oxygen available to the fire (also known as Ventilation-controlled)
